The present invention relates to a hinge assembly for rotatably coupling a hinged member to a device housing, and more particularly, to a position holding, self-latching hinge for holding a hinged member in one of an open position and a closed position relative to a device housing.
In certain hinge applications, it is desirable to provide a hinge which can maintain a hinged member in an open position or a closed position. When the hinged member is in the open position, in certain applications, such as portable communication devices (e.g., cellular and PCS phones) and in particular in clam shell style phones, it is desirable that the hinged member be held stably in position. It is also desirable in such applications that the hinge maintain the hinged member in a closed position relative to the device housing for storage and transport. Generally in such applications, the open position is set at a fixed, predetermined angle.
In the known devices, generally a spring bias member is installed between the hinged member and the device housing which biases the hinged element to the open position after an initial latching force is manually overcome or after a separate manual latch is released. However, the known hinge assemblies are provided in multiple pieces which are assembled in situ with the hinged member and the device housing. This type of known hinge imparts an axial force on the device housing and the hinged member and is costly to produce. While this additional loading can be accommodated for in the design of certain types of devices which have a sufficient size to provide the necessary load path, in the field of portable communication devices where the trend is to produce smaller and smaller phone devices, the use of this type of hinge assembly can result in premature fatigue and structural failure of the mounting provisions for the hinge in the device housing and/or hinged member.
In another known hinge which was designed to address the axial loading problem, a preassembled hinge is provided which can hold a hinged member in an open position or a closed position. The hinge includes an outer shell which reacts the axial spring load such that no axial force is imparted on the device housing or the hinged member. However, this construction is bulky, and cannot be installed between the device housing and the hinged member with a simple manufacturing operation. Additionally, the hinged member is not held stably in the open position since the closing and opening forces of the hinge are the same. In the open position the spring force on the hinge which acts to maintain the hinge in the open position is lower than when the hinge is in the closed position and, accordingly, the hinged member is subject to movement or chatter while in the open position. This can cause premature wear of the hinge as well as to the device housing and the hinged member which are connected by the hinge.
The present invention provides a relatively inexpensive preassembled, self-contained, two position hinge which can hold a hinged member in a first, open position or a second, closed position relative to a device housing without imparting an axial load on the hinged member or the device housing thereby resulting in long operating life (over 50,000 cycles). The hinge of the present invention can be simply and easily connected to the hinged member and the device housing without tools and with mere finger pressure yielding reduced assembly cost of the final product. Additionally, it would be desirable to control the stability of the hinged member in the open position relative to the device housing. It would also be desirable to provide for over travel of the hinged member without structural damage to the hinged member, the device housing or the hinge itself.